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WireGuard on OpenWRT based GL.iNET: some notes on the `wireguard_watchdog` script

Posted by jpluimers on 2026/01/15

On OpenWRT GL.iNET based devices, the WireGuard client does not restart upon reboot, even if it was started before rebooting.

Hopefully the /usr/bin/wireguard_watchdog script will help with this as others indicates it should.

My first try was no succes, but since it is supposed to run from cron it does no output. The script on GL-SFT1200 firmware version 3.215, script /usr/bin/wireguard_watchdog is different from the one in the OpenWRT repository, so it needs some investigation.

Some links for checking this out:

Queries:

–jeroen

[Wayback/Archive] GL-SFT1200 firmware version 3.215, script `/usr/bin/wireguard_watchdog`


#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# Copyright (C) 2018 Aleksandr V. Piskunov <aleksandr.v.piskunov@gmail.com>.
# Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
#
# This watchdog script tries to re-resolve hostnames for inactive WireGuard peers.
# Use it for peers with a frequently changing dynamic IP.
# persistent_keepalive must be set, recommended value is 25 seconds.
#
# Run this script from cron every minute:
# echo '* * * * * /usr/bin/wireguard_watchdog' >> /etc/crontabs/root
. /lib/functions.sh
check_peer_activity() {
local cfg=$1
local iface=$2
local public_key
local endpoint_host
local endpoint_port
local persistent_keepalive
local last_handshake
local idle_seconds
config_get public_key "${cfg}" "public_key"
config_get endpoint_host "${cfg}" "endpoint_host"
config_get endpoint_port "${cfg}" "endpoint_port"
persistent_keepalive=`wg show ${iface} persistent-keepalive | grep ${public_key} | awk '{print $2}'`
# only process peers with endpoints and keepalive set
[ -z ${endpoint_host} ] && return 0;
[ -z ${persistent_keepalive} -o ${persistent_keepalive} = "off" ] && return 0;
# skip IP addresses
# check taken from packages/net/ddns-scripts/files/dynamic_dns_functions.sh
local IPV4_REGEX="[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}"
local IPV6_REGEX="\(\([0-9A-Fa-f]\{1,4\}:\)\{1,\}\)\(\([0-9A-Fa-f]\{1,4\}\)\{0,1\}\)\(\(:[0-9A-Fa-f]\{1,4\}\)\{1,\}\)"
local IPV4=$(echo ${endpoint_host} | grep -m 1 -o "$IPV4_REGEX$") # do not detect ip in 0.0.0.0.example.com
local IPV6=$(echo ${endpoint_host} | grep -m 1 -o "$IPV6_REGEX")
[ -n "${IPV4}" -o -n "${IPV6}" ] && return 0;
# re-resolve endpoint hostname if not responding for too long
last_handshake=`wg show ${iface} latest-handshakes | grep ${public_key} | awk '{print $2}'`
[ -z ${last_handshake} ] && return 0;
idle_seconds=$((`date +%s`-${last_handshake}))
[ ${idle_seconds} -lt 150 ] && return 0;
logger -t "wireguard_monitor" "${iface} endpoint ${endpoint_host}:${endpoint_port} is not responding for ${idle_seconds} seconds, trying to re-resolve hostname"
wg set ${iface} peer ${public_key} endpoint "${endpoint_host}:${endpoint_port}"
}
# query ubus for all active wireguard interfaces
wg_ifaces=`ubus -S call network.interface dump | jsonfilter -e '@.interface[@.up=true]' | jsonfilter -a -e '@[@.proto="wireguard"].interface' | tr "\n" " "`
# check every peer in every active wireguard interface
config_load network
for iface in $wg_ifaces; do
config_foreach check_peer_activity "wireguard_${iface}" "${iface}"
done

view raw

wireguard_watchdog.sh

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This entry was posted on 2026/01/15 at 12:00 and is filed under *nix, *nix-tools, ash/dash, ash/dash development, Development, GL-AR300M, GL.iNet, GL.iNET GL-SFT1200, OpenWRT, Power User, Scripting, Software Development. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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